This invention relates to a Hall element that can be incorporated into an integrated circuit.
Devices of this type are, for example, used in wattmeters to measure an electric current i.sub.N or to form a voltage/current product u.sub.N. i.sub.N, where u.sub.N designates the supply voltage of an electric supply system and i.sub.N the electric current used by a consumer of electric energy. Since the current i.sub.N is proportional to the magnetic field H.sub.N it produces, the Hall element indirectly measures the current i.sub.N by determining the magnetic field H.sub.N. Since the output voltage V.sub.H of the Hall element is proportional to the product of i . H.sub.N, where i represents the supply current of the Hall element, the Hall element will also form the voltage/current product u.sub.N. i.sub.N, if the supply current i of the Hall element, for instance with the aid of a resistance, is selected in proportion to the supply voltage u.sub.N. In this case the Hall element has to work as a four-quadrant multiplier, as u.sub.N and i.sub.N, and also i and H.sub.N, are sine-shaped, thus having positive and negative values.
An integrated vertical Hall element is known from the publication "The vertical Hall-effect device", R. S. Popovic, IEEE Electron Device Letters, Vol. EDL-5, No. 9, September 84, pages 357-358. Vertical Hall elements are Hall elements which measure magnetic fields H.sub.N which are oriented parallel t the surface of the Hall element.
As concerns the stability, and especially the long-time stability of Hall elements, only some principles are known, as can, for example, be seen from the publication "Hall Effect Probes And Their Us In A Fully Automated Magnetic Measuring System", M. W. Poole and R. P. Walker, IEEE Transactions on Magnetics, Vol. MAG-17, No. 5, September 81, page 2132.